Results of dentine adhesion studies are influenced by many factors suc
h as intrinsic and extrinsic dentine wetness. Relative air humidity an
d temperature are extrinsic environmental factors whose influence on d
entine bonding capability is not precisely known. It was the aim of th
is study to gain an understanding of these factors as present in the m
ouths of patients and as influenced by several variables. In six diffe
rent experiments the influence of application of a rubber dam, high an
d low relative humidity in the dental surgery, nose and mouth breathin
g and tooth drying was investigated. The results show that without app
lication of a rubber dam there was no statistically significant differ
ence in temperature for the variables nose and mouth breathing and too
th drying (mean 27.7 +/- 1.5-degrees-C). Only the difference in relati
ve air humidity of the dental surgery was statistically significant. W
ith the application of a rubber dam the relative air humidity and temp
erature were essentially the same as the dental surgery conditions. It
is concluded that without rubber dam the intraoral environment in whi
ch bonding procedures are to be performed is comparable with a high hu
midity climate such as that of Central Africa or the South Pacific.